build-list will list which aports that has missing packages

rebuild-list will list which aports that has outdated packages, i.e. when
APKBUILD is newer than the apk

if there are an APKBUILD in current dir, then use ../ as repodir.
Otherwise, use cwd as repodir.

Introduces requirement of lua-filesystem

- provide a handle with aports.new(dir)
- provide foreach() helper functions

will recursively parse all build depends

ap is a helper script to parse APKBUILD and calculate build time
dependencies.